CHARACTERIZATION OF COHESIVE LAWS FOR FOAM-METAL INTERFACES

Abstract

Numerical prediction of mixed-mode failure along interfaces between polymeric foams and metals in foam-filled composite structures can be facilitated if interfacial cohesive laws are known. In this paper, we characterize the cohesive behavior of the interface between a polyurethane (PU) closed-cell foam and galvanized mild steel by extending an experimental approach suggested by [Lundsgaard–Larsen et al. [2008] Engineering Fracture Mechanics 75(8), 2514–2530]. A simplified approach for calculating the fracture energy and for extracting cohesive relations from the fracture energy-total crack opening displacement data is presented. We find that there is a substantial amount of normal separation in tests that are designed to be purely mode II, and a small amount of tangential motion in tests designed to be purely mode I. The interfacial cohesive laws extracted from our experiments suggest that the normal traction depends not only the normal and tangential displacements but also the tangential traction.